1. Field of the Invention:
This invention relates to an improved non-phasing chloroprene polymer adhesive composition and preparation thereof.
2. Description of the Prior Art:
Adhesive compositions comprising polychloroprene, metal oxide, an alkylphenol-formaldehyde resin and a solvent, having high adhesive strength are well known. These adhesive compositions are homogeneous and opaque when freshly prepared. However, when the adhesive compositions are stored for a long term, they have separated non-uniformly into an upper phase of transparent polychloroprene and the resin and a lower phase containing the sedimented metal oxide. When an inorganic filler is incorporated in the adhesive composition, the inorganic filler is sedimented together with the metal oxide. The phenomenon of separation into an upper phase and a lower phase is referred to as "phasing". When phasing of an adhesive composition occurs, the workability of a coating therefrom is low and a desirable adhesive strength cannot be obtained.
It is now believed that one reason for the phasing is that the polymerization of the chloroprene was conducted in the presence of a disproportionated rosin emulsifier.
A need exists, therefore, for a chloroprene adhesive which can be formed without use of a disproportionated rosin and hence will not phase.